I would say I have mixed porosity. Part of my length was previously colored multiple times and was heat styled on a regular basis. It seems quite possible that my natural hair is more towards the low porosity end of the spectrum though. Would be a great time to own a microscope.. :3

The differences between my preLHC and LHC hair:
-Dry time-the virgin hair will literally stay wet for 4-10 hours on the underside if I am not careful. This is made worse by any amount of oil or cones. The preLHC hair will be dry in 1 hour.

-Shine-the virgin hair has a natural shine while the preLHC hair is generally dull even with cones

-Tangling-my natural hair hardly tangles at all.. the preLHC hair also doesn't tangle much but it clings to itself more so.

-Poofiness-My virgin hair is much more likely to go limp and flat which I can't wait to see through my whole length

-Frizz-the virgin hair does still curl up a little more in humidity but it is much more frizz resistant. Before I would be a puff ball.

I think you can look at all of these factors to determine where your hair is on the porosity spectrum and it seems to be easier to just see changes over time on one's own head.